Tekkeitserktok from the Graph 100 forum is currently working on a new Zelda project for the Casio Graph 100 and AFX calculators.

So far you can only walk, enter the house and only the upper collision detection is done yet, but it features 4 level grayscale graphics (the screenshot program only support 3 level grayscale though so it should look a lot better on the real calculator) and it sound very promising. I added the project in the project section. A demo is currently avaliable here and you can check out for more info on the Graph 100 forum (in french):

http://www.graph100.com/forum/viewtopic.php?t=2819